error when using the user option to install

[yyzhang]

This issue is found by Marc Paterno -- only reported by yyzhang

When tying to install cluster_toolkit, here is the failure I get:

---

$ git clone https://github.com/tmcclintock/cluster_toolkit.git
$ cd cluster_toolkit/
$ python setup.py install --user
running install
error: can't combine user with prefix, exec_prefix/home, or install_(plat)base

Using the --user flag in order to reduce the likelihood of a collision between a system-wide installation and one's own account's stuff, and it would be nice if we can keep doing that.